CN114275735B - Mg-containing room-temperature reversible hydrogen storage high-entropy alloy powder material and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of hydrogen storage materials, and in particular relates to a room-temperature reversible hydrogen storage high-entropy alloy powder containing Mg and a preparation method thereof. The chemical formula of the material is Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1‑x , Wherein x=0.01～0.25. The present invention successfully prepares a high-entropy alloy powder containing Mg for reversible hydrogen storage at room temperature, and the prepared Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1‑x high-entropy alloy powder can contain up to 25 %, compared with traditional high-entropy alloys, a large amount of light element Mg is added, which greatly reduces the density of the alloy; at the same time, the prepared Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1‑x high-entropy alloy powder has The characteristics of reversible hydrogen storage at room temperature and high cycle stability, compared with other Mg-containing high-entropy alloys, have the outstanding effect of reversible hydrogen absorption and desorption at room temperature; the preparation method of the present invention is simple and easy to control, and the investment in production equipment is small. The production process is pollution-free and easy to industrialized large-scale production.

Description

A kind of room temperature reversible hydrogen storage high entropy alloy powder material containing Mg and its preparation method

technical field

The invention belongs to the technical field of hydrogen storage materials, in particular to a high-entropy alloy powder material containing Mg at room temperature for reversible hydrogen storage and a preparation method thereof.

Background technique

Hydrogen storage alloys can absorb and release hydrogen under certain conditions, and are safe and efficient hydrogen storage materials. Hydrogen storage alloys can be divided into the following categories: rare earth AB ₅ alloys (LaNi ₅ ); Mg hydrogen storage alloys (Mg and Mg ₂ Ni); titanium AB alloys (Ti-Fe, Ti-Mn); Laves Phase AB ₂ -type alloys (ZrMn ₂ , MgZn ₂ ); AB _3- type hydrogen storage alloys (PrNi ₃ , La-Mg-Ni) and V-based solid solutions with a BCC (body-centered cubic) structure. High-entropy alloys are composed of a variety of alloying elements and have the properties of a variety of alloying elements. Theoretically, adding alloying elements capable of storing hydrogen to high-entropy alloys and forming a BCC solid solution structure may enable high-entropy alloys to obtain hydrogen storage properties.

In terms of hydrogen storage performance, the hydrogen storage capacity of traditional hydrogen storage high-entropy alloys is generally lower than 2.0wt%, which is mainly because a large number of heavy metal elements (such as Zr, Nb, Mo, Hf, Ta) are added to the design for hydrogen storage. This is not conducive to obtaining a high hydrogen storage capacity. The existing design of high-entropy alloys for hydrogen storage is mainly improved on the basis of tradition, and the hydrogen storage capacity is increased by replacing heavy metal elements with transition metal elements. Compared with transition group metal elements, Mg has the advantages of high hydrogen storage capacity (theoretical hydrogen storage capacity is 7.6wt%), low density, wide range of sources and low price. Adding Mg to high-entropy alloys and forming BCC solid solutions can better reduce high The density of entropy alloys has the potential to further increase the hydrogen storage capacity.

However, there are many difficulties in the preparation of Mg-containing high-entropy alloys: first, the vapor pressure of Mg is high, and the preparation of Mg-containing high-entropy alloys by traditional arc melting and induction melting will lead to a large amount of Mg burning loss, which is not conducive to high-entropy alloys. The composition of entropy alloys is precisely controlled and industrialized; secondly, the crystal structure of Mg is HCP (hexagonal close-packed) structure, and the atomic radius of Mg is larger than that of transition metals. Therefore, it is difficult to form a BCC solid solution containing Mg.

Mechanical alloying is one of the conventional methods for preparing high-entropy alloys. Existing research mainly uses the ordinary planetary ball milling method to prepare magnesium-containing high-entropy alloys. Recently, Mg-containing high-entropy alloys have been developed such as MgAlTiFeNi and other alloys. These high-entropy alloys have deficiencies in the following aspects: 1) Most of the prepared high-entropy alloys contain impurity phases (such as various alloy phases and compound phases); 2) High-entropy alloys are prone to hydrogen-induced decomposition when absorbing and releasing hydrogen. The reversibility of hydrogen desorption is poor; 3) The hydrogen desorption temperature of the alloy is too high, generally above 300°C to dehydrogenate rapidly.

Therefore, how to design a Mg-containing high-entropy alloy capable of reversible hydrogen absorption and desorption at room temperature has important practical application value.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned problems existing in the traditional technology, provide a kind of Mg-containing room temperature reversible hydrogen storage high-entropy alloy powder material and its preparation method, convert the atomic ratio of the high-entropy alloy into mass ratio for the preparation of raw materials, Then, impurity-free FCC/BCC dual-phase Mg-containing high-entropy hydrogen storage alloy powders were prepared by high-speed vibration ball milling. The Mg-containing high-entropy hydrogen-storage alloy powder has a hydrogen storage capacity of 0.42-0.46wt% at room temperature; the dual-phase Mg-containing room-temperature reversible hydrogen-storage high-entropy alloy has the characteristics of simple preparation process, high efficiency, high yield, and no pollution. The highest content of Mg can reach 25%, and it has the remarkable advantage of rapid and reversible hydrogen storage at room temperature.

In order to achieve the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

A room temperature reversible hydrogen storage high entropy alloy powder material containing Mg, the chemical formula of the material is Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1-x , where x=0.01-0.25.

The preparation method of the above-mentioned Mg-containing room temperature reversible hydrogen storage high-entropy alloy powder material comprises the following steps:

1) Weigh five kinds of raw material metal powders of Mg, Ti, V, Nb and Cr according to the ratio, pour the weighed raw metal powders into the ball mill pot in the glove box, add grinding balls according to a certain ball-to-material ratio, and then pour Into n-heptane without grinding balls;

2) Seal the ball mill pot and place it on a high-speed vibrating ball mill for wet milling for a period of time, and cool to room temperature after the wet milling;

3) Remove the lid of the ball mill tank in the glove box and remove the n-heptane to obtain the high-entropy alloy powder material containing Mg at room temperature for reversible hydrogen storage.

Further, in step 1), the purity of Mg powder is ≥99.5%, the purity of Ti, V, Nb and Cr raw material metal powder is ≥99%, and the particle size of all raw material powders is not less than 200 mesh.

Further, in step 1), the ball-to-material ratio is 20-30:1.

Further, in step 1), the purity of n-heptane is ≥99%.

Further, in step 2), the ball milling tank is a stainless steel ball milling tank, the grinding balls are stainless steel grinding balls, and the feeding operation is performed in a glove box.

Further, in step 2), the wet milling time is 30-40 hours.

Further, in step 2), the vibration frequency of the n-heptane high-speed vibration ball mill is 1200 cycles/min, and stops for 10 minutes every 30 minutes of operation.

Further, in step 3), the operation of removing n-heptane is: use a rubber dropper to extract the n-heptane above the powder, and remove the remaining small amount of n-heptane by vacuuming the transition chamber.

Further, the time for vacuuming by using the transition chamber is 1-2 hours.

The alloy design of the present invention is improved on the equiatomic ratio TiVNbCr, on the basis of ensuring the general design principles of high-entropy alloy design (δ<10%,-15<ΔHmix<5kJ/mol and Ω≥1.1), the atomic radius is small The content of the Cr element is reduced to 10%, which increases the average atomic radius of the alloy and facilitates the addition of Mg; slightly reduces the content of the denser Nb element; this adjustment method can make it easier to add more large atomic radii to the alloy The light element Mg and reduce the density of the alloy; the addition of the alloying element Mg can significantly reduce the density of the alloy. The preparation method adopts the method of high-speed vibrating balls. High-speed vibrating ball milling is a new type of mechanical alloying method that combines planetary motion and vertical high-frequency vibration. Through this compound complex high-energy motion, impact, friction, and shear are generated between materials. , which greatly promotes the mutual diffusion and interaction between atoms, greatly increases the mixing entropy of the material system, and is more conducive to the formation of multi-component high-entropy alloys.

The beneficial effects of the present invention are:

1. The present invention has successfully prepared a high-entropy alloy powder containing Mg for reversible hydrogen storage at room temperature, and the Mg content that can be added to the prepared Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1-x high-entropy alloy powder is the highest. Up to 25%, compared with traditional high-entropy alloys, a large amount of light element Mg is added, which greatly reduces the density of the alloy.

2. The Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _1-x high-entropy alloy powder prepared by the present invention has the characteristics of reversible hydrogen storage at room temperature and high cycle stability. Compared with other Mg-containing high-entropy alloys, the present invention It has the outstanding effect of reversible hydrogen absorption and desorption at room temperature.

3. The preparation method of the present invention is simple and easy to control, with less investment in production equipment, no pollution in the production process, and easy industrialized large-scale production.

Of course, implementing any product of the present invention does not necessarily need to achieve all the above advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that are required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

Figure 1 is an X-ray diffraction pattern of Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 Mg-containing high-entropy alloy powder;

Figure 2 is the hydrogen absorption and desorption diagram of Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 Mg-containing high-entropy alloy powder;

Figure 3 is an X-ray diffraction pattern of Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 Mg-containing high-entropy alloy powder;

Figure 4 is the hydrogen absorption and desorption diagram of Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 Mg-containing high-entropy alloy powder;

Figure 5 is the X-ray diffraction pattern of Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 high-entropy alloy powder;

Figure 6 is the hydrogen absorption and desorption diagram of Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 high-entropy alloy powder;

Fig. 7 is a 10-cycle hydrogen absorption capacity diagram of the high-entropy alloy powder.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Specific embodiments of the present invention are as follows:

Example 1

Weigh Mg (particle size 200 mesh, purity 99.5 _% ) _{, Ti , V} , _Nb and Cr powder (particle size 200 mesh, purity 99% ) a total of 5 grams. Put the weighed elemental metal powder into a stainless steel ball milling tank, add stainless steel grinding balls at a ball-to-material ratio of 20:1, then pour ultra-dry n-heptane (purity greater than 99%) over the stainless steel balls, and seal the ball milling tank cover. Put the ball mill pot in a high-speed vibrating ball mill for wet ball milling for 30 hours. The shimmy frequency of the ball mill is 1200 cycles/min, and it stops for 10 minutes every 30 minutes. After the ball milling, the n-heptane above the powder was drawn out with a rubber dropper in the glove box, and the remaining small amount of n-heptane was removed by vacuuming the transition chamber for 1 hour to obtain Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 Dual-phase Mg-containing high-entropy hydrogen storage alloy powder (see Figure 1: Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 Dual-phase Mg-containing high-entropy alloy powder X ray diffraction pattern). The high-entropy alloy powder can reversibly store hydrogen at room temperature, with a capacity of about 0.44wt.% (see Figure 2: Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 Mg-containing high-entropy alloy powder hydrogen absorption and desorption diagram); 10 cycles of hydrogen absorption at room temperature have a reversible capacity of 94% (see b in Figure 7: Mg _0.1 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.9 high-entropy alloy powder 10 cycle hydrogen absorption capacity diagram).

Example 2

Weigh Mg (particle size 200 mesh, purity _99.5 %) _{, Ti} , _V , _Nb and Cr powder ( _particle size 200 mesh, purity 99% ) a total of 5 grams. Put the weighed elemental metal powder into a stainless steel ball milling tank, add stainless steel grinding balls at a ball-to-material ratio of 20:1, then pour ultra-dry n-heptane (purity greater than 99%) over the stainless steel balls, and seal the ball milling tank cover. Put the ball mill pot in a high-speed vibrating ball mill for wet ball milling for 30 hours. The shimmy frequency of the ball mill is 1200 cycles/min, and it stops for 10 minutes every 30 minutes. After the ball milling, the n-heptane above the powder was extracted with a rubber dropper in the glove box, and the remaining small amount of n-heptane was removed by vacuuming the transition chamber for 2 hours to obtain Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 dual-phase Mg-containing high-entropy hydrogen storage alloy powder (see Figure 3: X-ray diffraction pattern of Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 high-entropy alloy powder) . High-entropy alloy powders can reversibly store hydrogen at room temperature, with a capacity of about 0.42wt.% (see Figure 4): Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 Hydrogen absorption and desorption diagram of Mg-containing high-entropy alloy powders) ; 10 cycles of hydrogen absorption at room temperature have a reversible capacity of 94.7% (see c in Figure 7: Mg _0.2 (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _0.8 high-entropy alloy powder 10 cycle hydrogen absorption capacity diagram).

comparative example

According to the composition of Ti _0.35 V _0.35 Nb _0.2 Cr _0.1, 5 grams of Ti, V, Nb and Cr powders (particle size 200 mesh, purity 99%) were weighed in the glove box. Put the weighed elemental metal powder into a stainless steel ball milling tank, add stainless steel grinding balls at a ball-to-material ratio of 20:1, then pour ultra-dry n-heptane (purity greater than 99%) over the stainless steel balls, and seal the ball milling tank cover. Put the ball mill pot in a high-speed vibrating ball mill for wet ball milling for 40 hours. The shimmy frequency of the ball mill is 1200 cycles/min, and it stops for 10 minutes every 30 minutes. After the ball milling, the n-heptane above the powder was drawn out with a rubber dropper in the glove box, and the remaining small amount of n-heptane was removed by vacuuming the transition chamber for 2 hours to obtain Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 dual phase high entropy hydrogen storage alloy powder. (See Figure 5: X-ray diffraction pattern of Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 high-entropy alloy powder); high-entropy alloy powder can reversibly store hydrogen at room temperature, with a capacity of about 0.46wt.% (see 6: Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 Mg-containing high-entropy alloy powder hydrogen absorption and desorption diagram); 10 cycles of hydrogen absorption at room temperature have a reversible capacity of 93% (see a in Figure 7: Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 high-entropy alloy Hydrogen absorption capacity diagram of the powder for 10 cycles).

The preferred embodiments of the invention disclosed above are only to help illustrate the invention. The preferred embodiments do not exhaust all details nor limit the invention to specific implementations. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents.

Claims (9)

1. A room temperature reversible hydrogen storage high-entropy alloy powder material containing Mg, characterized in that: the chemical formula of the material is Mg _x (Ti _0.35 V _0.35 Nb _0.2 Cr _0.1 ) _{1- x} , where x=0.01~0.25. 2. the preparation method of Mg-containing room temperature reversible hydrogen storage high-entropy alloy powder material according to claim 1, is characterized in that, comprises the steps: 1) Weigh the five raw material metal powders of Mg, Ti, V, Nb, and Cr according to the proportion, pour the weighed raw metal powder into the ball mill pot in the glove box, add grinding balls according to a certain ball-to-material ratio, and then pour Into n-heptane without grinding balls; 2) After sealing the ball mill jar, place it on a high-speed vibrating ball mill for wet milling for a period of time, and cool to room temperature after wet milling; 3) Remove the lid of the ball mill tank in the glove box and remove the n-heptane to obtain the high-entropy alloy powder material containing Mg at room temperature for reversible hydrogen storage. 3. The preparation method according to claim 2, characterized in that: in step 1), the purity of Mg powder is ≥99.5%, the purity of Ti, V, Nb and Cr raw material metal powder is ≥99%, and the particle size of all raw material powders is not Less than 200 mesh. 4. The preparation method according to claim 2, characterized in that: in step 1), the ball-to-material ratio is 20-30:1. 5. The preparation method according to claim 2, characterized in that: in step 1), the purity of n-heptane is ≥99%. 6. The preparation method according to claim 2, characterized in that: in step 2), the wet grinding time is 30-40 hours. 7. The preparation method according to claim 2, characterized in that: in step 2), the shimmy frequency of the n-heptane high-speed vibrating ball mill is 1200 cycles/min, and stops for 10 minutes every 30 minutes of operation. 8. The preparation method according to claim 2, characterized in that: in step 3), the operation of removing n-heptane is: use a rubber dropper to extract the n-heptane above the powder, and use a transition method for the remaining small amount of n-heptane The method of vacuumizing the warehouse is removed. 9. The preparation method according to claim 8, characterized in that: the vacuuming time is 1-2 hours.

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